An understanding of the fate of heavy metals in the environment is linked to an understanding of the speciation of metal ions in the environment. Heavy metal ions are transformed by both abiotic and biotic processes. Biological removal and transformation of heavy metals by bacteria, fungi and plants can have a significant contribution to the fate of metal ions in the environment which must be taken into consideration when evaluating the mobility of metal ions in the environment, the suitability of a site for remediation, or the progress of a site undergoing remediation. We propose to characterize the transformation of heavy metal ions by plants using XAS to characterize Ni and Cr accumulation by plant tissue culture, both on the cell wall and within the plant cell.